What is a Ferrox Trout? [Archive] - Fly Fishing Forum

: What is a Ferrox Trout?

09-16-2004, 02:56 PM
Hey All

While daydreaming my way through some Scottish Fly fishing websites I saw Ferrox Trout come up a number of times. I looked it up on Fishbase.org but drew a blank. A search on just that name seems to bring up more Scottish sites but none have a photo on them. Is this this just a local name for a trout or salmon that I might already know of?



Willie Gunn
09-16-2004, 03:23 PM
Ferox Trout
A ferox trout is is a trout which has turned cannibal. Juvenile trout live on insects and grubs, but when a brown trout reaches about 12" in length it can change diets. At that size it can catch and eat other fish up to half its own length. Such a sizeable meal is rich in protein and may require less effort to obtain. As a result trout which discover this food source soon pack on the weight. Growth curves which may have been gentle can now explode. Not very many trout take this option, perhaps due to a lack of prey fish. Some lochs such as Rannoch are famous for their ferox, these lochs often have good heads of charr and perch as a food source. Loch Tay has given up ferox to 16lb in recent years. See more about ferox trout fishing.

w ww.fishingnet.com/brown_trout.htm

To some naturalists a ferox or great lake trout is simply a large brown trout that feeds primarily on fish. To others it is a species of trout in its own right, the Salmo ferox. But all agree on the main characteristics of the ferox: a big wild trout that is found in natural lakes in Europe; with a big head and grotesquely long, broad powerful jaws that bear some resemblance to the pike's; a fairly plain silvery or dull brown coloration, possibly with a greenish or olive hue; a fish-eater. To these physical features we must add one other ferox characteristic: great longevity.

Most of the British and Irish lakes that appear to hold ferox trout tend to be fairly unproductive: lakes like Lochs Morar, Ness, Arkaig, Awe and Quoich in Scotland, Ullswater and Bassenthwaite in Cumbria, Loughs Eask and Melvin. in Ireland and Llyns Padarn and Peris set amidst the mountains of Snowdonia. In these waters a typical brown trout caught on rod and line will be less than a pound in weight and between three and five years of age. But very occasionally the angling press will announce the capture of a trout weighing up to ten pounds or more.

There is considerable evidence that the number of big ferox trout has declined during this century. In the 1800s they were not uncommon, but a wild ten-pounder is now a rarity. This may be related to the decline of the Atlantic salmon and sea trout, on which the ferox feed. Most ferox lakes have adults of these species passing through them to spawn in the lakes' feeder streams. After spawning, the much-weakened kelts drop back to the lakes; and two or three years later the sea-going smolts pass through the lake on their way to the sea. These are the ferox's prey; and the great reduction in numbers of these rich sources of food has presumably contributed to the scarceness of big ferox.

In a study of Lough Melvin, biologists from the Queen's University, Belfast showed that the ferox trout is genetically different from the other forms of trout that inhabit that lake. They spawn with other ferox trout in separate streams from the other trout that live there. Furthermore, Andrew Ferguson and his co-workers showed that it is possible to identify, by genetic finger-printing, tiny ferox trout that may superficially resemble ordinary brown trout. On these grounds Ferguson argued, in the Went Memorial Lecture given to the Royal Dublin Society on 20 November 1985, that the ferox in Melvin were a full species in their own right that had evolved from a single colonisation of the lough follow'mg the last Ice Age.

As yet, we have no similar studies from other ferox lakes, so the biological identity of the ferox remains a puzzle. If ferox are merely overgrown carnivorous trout, why do some trout become fish-eaters and grow to great age and size while the vast majority do not? But if ferox are members of a separate species, why are there no records in the angling literature of small ferox trout?

Only the most tentative conclusions can be drawn at present. Briefly, within the brown trout stocks of some lakes are genes which confer on their possessors the ability to grow to great age and to great size, and a behavioural trait to turn almost exclusively to a diet of fish once they have reached a certain size. Other trout, the majority, do not have these genes; they have a much shorter lifespan and although like all trout they will feed keenly on very small fish fry at times, they will not change their feeding pattern to concentrate on hunting fish.

w ww.lochwinnochac.net/Trout/ferox.html

Whole new study, no one is sure but IMHO they are just big cannibel brownies.

09-16-2004, 03:32 PM
Thanks for the in-depth (and speedy!) reply!

09-24-2004, 03:49 AM
Just cos I know a bit about this I can't help myself from sharing....

As indicated above there are two types of ferox.

The first is the genetically distinct ferox trout, which as in Melvin exists as a seprate species and breeds only with other ferox trout. These are associated with cold upland low productivity lakes, just like char in Ireland.

The second is the trout which turn on to a fish diet and become ferox like in appearance. These are not only found in low productivity waters. Indeed the famous Lough Corrib gives up a large number of "ferox" to those who troll for them, especially in the early season.

The Irish Specimen Fish Committee website carries an article on angling for these Corrib fish. www.irish-trophy-fish.com/articles/bobc.htm

The Irish Char Conservation Group has a bit about ferox on their website (our website I should say) and also about sonaghen and gillaroo - other fully fledged species of brown trout. There is also a photo of a small ferox from lough Talt. www.charr.org/species/ferox.htm

Appart from the interest some of you may have in these article I have to say Willie has it covered above.

On a more general note fishing was slow for me in 2004. Some great sport was had to the middle of June on my local river the Liffey. Fish of a pound and more were not uncommon and I really enjoyed fishing smaller and smaller as the evenings got longer and longer. But I eventaully had reign in my enthousiasm for the trout and give my new daughter a bit of attention(!). At 7 pounds she was a lot smaller than some fish I have know, but she makes up in smiles what she lacks in size.

I can really appreciate all those posts that allude to good fishing opportunites interrupted by family commitments now...

09-24-2004, 12:51 PM
Thanks Mylo! Next time I head your way I will have to try for a ferox or two.